This application claims the priority benefit of Taiwan application serial no. 88115535, filed Sep. 9, 1999.
1. Field of the Invention
The present invention relates to an installation for measuring pressure inside a vacuum pipeline. More particularly, the present invention relates to an installation that utilizes a control valve to protect a vacuum gauge.
2. Description of the Related Art
FIG. 1 is a schematic diagram showing a conventional vacuum pipeline system with connection to a vacuum gauge. A Tel Alpha-8S-Z furnace station 10 works in a high vacuum. In operation, some exhaust gases are produced inside the reaction chamber of the station 10. A vacuum pipeline is used to remove the exhaust gases from the reaction chamber 20. The exhaust gases pass through a trap 30. The trap 30 is a device for removing some of the micro-particles produced inside the reaction chamber 20. The exhaust gases subsequently pass through a main valve (MV) 40 to be drawn away by a pump 50. A vacuum gauge 60 is installed somewhere (at point A) along a pipeline section between the trap 30 and the main valve 40. The vacuum gauge is a device for measuring pressure in the reaction chamber 20 and along the pipeline.
As soon as a high vacuum is created inside the reaction chamber 20 of the station 10 using the pump 50, desired chemical reactions can be carried out inside the reaction chamber 20. However, the vacuum gauge 60 is mounted directly at some point along the pipeline. Since volatile substance from the reaction chamber 20 is carried along the pipeline, a portion of the substance is deposited on the cooler interior surface of the vacuum gauge 60. After the vacuum gauge 60 has been in use for some time, it is coated with a thick residual layer, leading to a shifting of the measured pressure. If the coated layer is thick, sometimes a value of just 720 torrs or lower is shown when the actual pipeline pressure is about one atmosphere (760 torr). An erroneous pressure from a faulty vacuum gauge is likely to compromise pressure control capability. Hence, product quality may be affected. Another effect on the vacuum gauge 60 due to the accumulation of emission material from the reaction chamber is a shortening of working life. Ultimately, frequency of maintenance of the station 10 has to increase resulting in a reduction of production efficiency.
According to repeated trials, a vacuum gauge is mounted directly onto the vacuum pipeline can have a working life of at most 3 months. For a production facility having many stations, maintaining all the vacuum gauges in proper working conditions is a daunting task and is very expensive.
Accordingly, one object of the present invention is to provide an installation for measuring pressure inside a vacuum pipeline that couples to a reaction chamber. The installation includes a control valve between the pipeline and a vacuum gauge. The vacuum gauge is shut when chemical reactions are conducted inside the reaction chamber so that material emitted from the reaction chamber is prevented from coating the interior surface of the vacuum gauge.
A second object of the invention is to provide an installation for measuring pressure inside a vacuum pipeline capable of preventing a gradual shifting of the measured pressure relative to the actual value. Hence, working life of the vacuum gauge is increased.
The invention provides an installation for measuring pressure inside a vacuum pipeline. The installation includes a pipe section, a control valve, a vacuum gauge and a control circuit. The pipe section branches from the pipeline, creating a separate path. The control valve is attached to the other end of the pipe section for opening and closing the pipe section. The vacuum gauge is connected to the control valve for measuring the pressure inside the pipeline when the control valve is opened. The control circuit is coupled between the control valve and a control device on a main valve. The control circuit shuts the control valve a preset period after the main valve is opened and opens the control valve immediately after the main valve is shut.
Through the opening and closing of a control valve using a control circuit, the coating of emission material onto the interior surface of the vacuum gauge is prevented. Consequently, working life of the vacuum gauge is extended.
This invention provides a vacuum pipeline installation that connects between a processing station and a pump for measuring pressure. The installation includes a vacuum pipeline, a pipe section, a control valve, a vacuum gauge and a control circuit. The input end of the trap is connected to the processing station. One end of the vacuum pipeline is connected to the output end of the trap. The input end of the main valve is connected to the other end of the pipeline, while the output end of the main valve is connected to the pump. One end of a pipe section is attached to a point somewhere along the pipeline between the trap and the main valve so that a branch from the pipeline is formed. One end of a control valve is connected to the other end of the pipe section for opening and closing the pipe section. The vacuum gauge is connected to the other end of the control valve for measuring pressure along the pipeline when the control valve is opened. The control circuit is coupled between the main valve and the control valve. The control circuit shuts the control valve a preset period after the main valve is opened and opens the control valve immediately after the main valve is shut.
This invention also provides a vacuum pipeline system. The system includes a processing station having a reaction chamber, a vacuum pipeline, a pipe section, a control valve, a vacuum gauge, a control circuit and a pump. The input end of the trap is connected to the processing station, and the output end of the trap is connected to one end of the vacuum pipeline. The input end of the main valve is connected to the other end of the pipeline, while the output end of the main valve is connected to the pump. One end of a pipe section is connected to a point somewhere along the pipeline between the trap and the main valve so that a branch from the pipeline is formed. One end of a control valve is connected to the other end of the pipe section for opening and closing the pipe section. The vacuum gauge is connected to the other end of the control valve for measuring pressure along the pipeline when the control valve is opened. The control circuit is coupled between the main valve and the control valve. The control circuit shuts the control valve a preset period after the main valve is opened and opens the control valve immediately after the main valve is shut.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.